Control of dynamic brightness of light-emitting diode array

ABSTRACT

An apparatus includes a light-emitting diode (LED) driver circuit, one or more LEDs of an LED array, and an electronic switching circuit. The LED driver circuit is configured to generate an electric current. The one or more LEDs are electrically connected to the LED driver circuit. The electronic switching circuit is electrically connected to the one or more LEDs and configured to be placed in one of multiple switching configurations. The electronic switching circuit is further configured to direct a portion of the electric current away from the one or more LEDs, such that a remaining portion of the electric current drives the one or more LEDs. The portion of the electric current corresponds to the one of the multiple switching configurations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/126,592, filed on Dec. 18, 2020, which claims priority to U.S.Application Ser. No. 62/950,324, filed on Dec. 19, 2019, which arehereby incorporated by reference in their entirety.

TECHNICAL FIELD

This disclosure relates to methods and apparatuses for controlling thedynamic brightness of a light-emitting diode (LED) array, such as in anelectronic display or an LED lighting system.

BACKGROUND

Traditional lighting controller circuits used to drive electronicdisplays and other lighting systems sometimes provide a relativelynarrow range of brightness. The narrow range of brightness can affectuser experience especially when projecting light under dim ambient lightconditions where less overall brightness is desired. Moreover,electronic displays or other lighting systems that are too bright canincrease the power consumption as well as increase the visibility ofoptical artifacts.

SUMMARY

Innovative aspects of the subject matter described in this specificationinclude methods and apparatuses for controlling a light-emitting diode(LED) array. An apparatus for controlling an LED array includes an LEDdriver circuit, one or more LEDs of the LED array, and an electronicswitching circuit. The LED driver circuit is configured to generate anelectric current. The one or more LEDs are electrically connected to theLED driver circuit. The electronic switching circuit is electricallyconnected to the one or more LEDs and configured to be placed in one ofmultiple switching configurations. The electronic switching circuit isfurther configured to direct a portion of the electric current away fromthe one or more LEDs, such that a remaining portion of the electriccurrent drives the one or more LEDs. The portion of the electric currentcorresponds to the one of the multiple switching configurations.

Innovative aspects of the subject matter described in this specificationfurther include methods and apparatuses for controlling an LED array. Anapparatus for controlling an LED array includes one or more LEDs of theLED array, a first programmable LED driver circuit electricallyconnected to the one or more LEDs, and a second programmable LED drivercircuit electrically connected to the one or more LEDs. The firstprogrammable LED driver circuit is configured to be placed in one of afirst set of configurations. The first programmable LED driver circuitis further configured to generate a first electric current correspondingto the one of the first set of configurations. The second programmableLED driver circuit is configured to be placed in a second one of asecond set of configurations. The second programmable LED driver circuitis further configured to generate a second electric currentcorresponding to the second one of the second set of configurations. Thefirst electric current and the second electric current are combined intoa third electric current to drive the one or more LEDs.

Among other benefits and advantages, the embodiments disclosed hereinincrease the range of dynamic brightness of a red-green-blue (RGB) LEDarray compared to traditional methods by decreasing the minimumbrightness limits of LEDs that are powered by an LED driver circuit. Theembodiments provide an improved user experience for users of RGBdisplays, especially under conditions of dim lighting. The embodimentsalso enable lower power consumption compared to traditional LEDcontrollers by extending the dynamic range of display brightness.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other potential features, aspects, and advantages ofthe subject matter will become apparent from the description, thedrawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an apparatus for controlling a light-emitting diode(LED) array.

FIG. 2 illustrates an apparatus for controlling an LED array.

FIG. 3 illustrates an apparatus for controlling an LED array.

FIG. 4 illustrates an apparatus for controlling an LED array.

FIG. 5 illustrates an apparatus for controlling an LED array.

FIG. 6 is a flowchart showing operations in methods for controlling anLED array.

FIG. 7 is a flowchart showing operations in methods for controlling anLED array.

DETAILED DESCRIPTION

FIG. 1 illustrates an apparatus for controlling a light-emitting diode(LED) array. An LED array can be used in an electronic display, such asin a device (e.g., headset) that provides a virtual reality, augmentedreality, or mixed reality experience. An LED array can also be used toprovide illumination in aviation lighting systems, automotive headlamps,traffic signals, cameras, medical devices, and/or other suitablesystems. The apparatus illustrated in FIG. 1 includes a controllercircuit 100, an LED driver circuit 108, one or more LEDs 112 of the LEDarray, and an electronic switching circuit 128. The LED driver circuit108 is configured to generate an electric current 116 to power the oneor more LEDs 112. In some embodiments, the electric current 116generated by the LED driver circuit 108 is in a range from 20 mA to 400mA. The amount of the electric current 116 will depend on the type ofthe LED driver circuit 108 used. The one or more LEDs 112 areelectrically connected to the LED driver circuit 108 to be powered bythe LED driver circuit 108.

The electronic switching circuit 128 includes an electronic switch 120and a resistor 124. The electronic switching circuit 128 is electricallyconnected to the one or more LEDs 112. The electronic switching circuit128 is configured to be placed in one of multiple switchingconfigurations. For example, when the electronic switch 120 is open, theelectronic switching circuit 128 is placed in a first switchingconfiguration in which the electric current 116 flows through the one ormore LEDs 112 to drive the one or more LEDs 112 one at a time. Each LEDof the one or more LEDs 112 is connected to a separate pulldown circuitwithin the LED driver circuit 108. In some embodiments, the controllercircuit 100 is configured to generate control signals 104 that activateonly one of the one or more pulldown circuits at a time. Hence, only oneof the one or more pulldown circuits is active at a time. Hence, onlyone of the one or more LEDs 112 is driven at a time.

When the electronic switch 120 is closed, the electronic switchingcircuit 128 is placed in a second switching configuration. In the secondswitching configuration, the electronic switching circuit 128 isconfigured to direct a portion 132 of the electric current 116 away fromthe one or more LEDs 112 and through the resistor 124. A remainingportion 136 of the electric current 116 drives the one or more LEDs 112.The portion 132 of the electric current 116 corresponds to the switchingconfiguration that the electronic switching circuit 128 is placed in.For example, in the first switching configuration, the portion 132 iszero. In the second switching configuration when the electronic switch120 is closed, the portion 132 corresponds to the voltage drop acrossthe electronic switching circuit 128 divided by a resistance of theresistor 124. In some embodiments, the remaining portion 136 of theelectric current 116 is in a range from 0 mA to 380 mA. Hence, thebrightness of each LED of the 112 is decreased when driven by theremaining portion 136 instead of the electric current 116.

In the apparatus illustrated in FIG. 1 , each LED of the one or moreLEDs 112 has a first brightness responsive to being driven by theelectric current 116. When the electronic switching circuit 128 is notused, the minimum brightness limit of the LED array corresponds to theminimum limit on the electric current 116 generated by the LED drivercircuit 108. Each LED of the one or more LEDs 112 has a secondbrightness responsive to being driven by the remaining portion 136 ofthe electric current 116. When the electronic switching circuit 128 isused, the minimum brightness limit of the LED array corresponds to theminimum limit on the remaining portion 136 of the electric current 116.The remaining portion 136 of the electric current 116 is less than theelectric current 116. Hence, the second brightness is less than thefirst brightness. Therefore, when the electronic switching circuit 128is used, the minimum brightness limit of the LED array is reducedcompared to when the electronic switching circuit 128 is not used.

FIG. 2 illustrates an apparatus for controlling an LED array. Theapparatus illustrated in FIG. 2 includes an LED driver circuit 200, oneor more LEDs 204 of the LED array, and an electronic switching circuit256. The LED driver circuit 200 is configured to generate an electriccurrent 208 to power the one or more LEDs 204. The one or more LEDs 204are electrically connected to the LED driver circuit 200 to be poweredby the LED driver circuit 200.

The electronic switching circuit 256 is electrically connected to theone or more LEDs 204. In some embodiments, the electronic switchingcircuit 256 includes multiple electronic switches (216, 220, 224, . . ., 228) electrically connected in a first parallel configuration. Theelectronic switching circuit 256 further includes multiple resistors(240, 244, 248, . . . , 252) electrically connected in a second parallelconfiguration. Each electronic switch, for example, the electronicswitch 216, is electrically connected to one or more correspondingresistors, for example the resistor 240.

The multiple electronic switches are configured to place the electronicswitching circuit 256 in one of multiple switching configurations. Theelectronic switching circuit 256 is configured to be placed in aparticular switching configuration by closing different combinations ofthe multiple electronic switches. In each switching configuration, theelectronic switching circuit 256 directs a portion 212 of the electriccurrent 208 away from the one or more LEDs 204, such that a remainingportion 260 of the electric current 208 drives the one or more LEDs 204.The portion 212 of the electric current 208 corresponds to the switchingconfiguration that the electronic switching circuit 256 has been placedin.

The resistors (240, 244, 248, . . . , 252) are electrically connected tothe multiple electronic switches (216, 220, 224, . . . , 228) andconfigured to direct the portion 212 of the electric current to a port236 of the LED driver circuit 200. The portion 212 of the electriccurrent 208 flowing through one or more of the resistors (240, 244, 248,. . . , 252) and the remaining portion 260 of the electric current 208driving the one or more LEDs 204 are combined into an electric current232 and directed to the port 236 of the LED driver circuit 200.

In some embodiments, the electronic switching circuit 256 includes Nelectronic switches, wherein N is greater than or equal to 1. Forexample, N can be 1, 17, 124, etc., The electronic switching circuit 256can thus be placed in one of 2^(N) switching configurations at a time byclosing different combinations of the electronic switches. For example,consider an embodiment in which N is 4. In a first switchingconfiguration, all the four electronic switches (216, 220, 224, 228) areopen and the portion 212 of the electric current 208 is zero. In asecond switching configuration, the electronic switch 216 is closed andthe remaining three electronic switches (220, 224, 228) are open. In athird switching configuration, the electronic switches 216, 220 areclosed and the electronic switches 224, 228 are open. In a sixteenthswitching configuration, all the four electronic switches (216, 220,224, 228) are closed.

The portion 212 of the electric current 208 varies in accordance withthe switching configuration that the electronic switching circuit 256 isplaced in. For example, the portion 212 of the electric current 208varies in accordance with the resistance of the electronic switchingcircuit 256. Hence, the remaining portion 260 of the electric current208 varies in accordance with the switching configuration that theelectronic switching circuit 256 is placed in. Because the brightness ofeach LED of the one or more LEDs 204 varies in accordance with theremaining portion 260 of the electric current 208, the brightness ofeach LED varies in accordance with the switching configuration that theelectronic switching circuit 256 is placed in. By closing differentcombinations of the electronic switches (216, 220, 224, 228), thebrightness of the LED array is varied.

In some embodiments, the electronic switching circuit 256 includes oneor more variable resistors. For example, one or more of the resistors(240, 244, 248, . . . , 252) can be a variable resistor. The resistanceof each variable resistor can be adjusted by a controller circuit, suchas the controller circuit 100 illustrated in FIG. 1 . Hence, the portion212 of the electric current 208 can be adjusted by adjusting theresistance of each variable resistor.

FIG. 3 illustrates an apparatus for controlling an LED array. Theapparatus illustrated in FIG. 3 includes an LED driver circuit 300, oneor more LEDs 312 of the LED array, and an electronic switching circuit316. The LED driver circuit 300 is configured to generate an electriccurrent to power the one or more LEDs 312. The one or more LEDs 312 areelectrically connected to the LED driver circuit 300 to be powered bythe LED driver circuit 300.

The electronic switching circuit 316 includes one or more electronicswitches 304 and one or more resistors 308. The one or more LEDs 312 areelectrically connected to each other in a series configuration. Eachelectronic switch of the one or more electronic switches 304 iselectrically connected to a corresponding LED of the one or more LEDs312 and a corresponding resistor of the one or more resistors 308. Whena particular electronic switch of the one or more electronic switches304 is closed, the electronic switching circuit 316 directs a portion ofthe electric current away from the corresponding LED, such that aremaining portion of the electric current drives the corresponding LED.Hence, a brightness of the corresponding LED is reduced compared to thebrightness of the corresponding LED when the particular switch is open.Hence, the brightness of the LED array can be varied by closingdifferent combinations of the one or more electronic switches 304.

FIG. 4 illustrates an apparatus for controlling an LED array. Theapparatus illustrated in FIG. 4 includes one or more LEDs 436 of the LEDarray, a first programmable LED driver circuit 412, a secondprogrammable LED driver circuit 416, and a controller circuit 400. Thefirst programmable LED driver circuit 412 is electrically connected tothe one or more LEDs 436 and configured to power the one or more LEDs436. The first programmable LED driver circuit 412 is configured to beplaced in one of a first set of configurations. In each of the first setof configurations, the first programmable LED driver circuit 412generates a first electric current 420 to power the one or more LEDs436. The first electric current 420 corresponds to the configurationthat the first programmable LED driver circuit 412 is placed in. Thecontroller circuit 400 is electrically connected to the firstprogrammable LED driver circuit 412. The controller circuit 400 isconfigured to place the first programmable LED driver circuit 412 ineach of the first set of configurations to adjust the first electriccurrent 420. For example, the controller circuit 400 generates controlsignals 408 that place the first programmable LED driver circuit 412 ineach configuration.

The second programmable LED driver circuit 416 is configured to beplaced in a second one of a second set of configurations. In each of thesecond set of configurations, the second programmable LED driver circuit416 generates a second electric current 424 to power the one or moreLEDs 436. The second electric current 424 corresponds to theconfiguration that the second programmable LED driver circuit 416 isplaced in. The controller circuit 400 is electrically connected to thesecond programmable LED driver circuit 416. The controller circuit 400is configured to place the second programmable LED driver circuit 416 ineach of the second set of configurations to adjust the second electriccurrent 424. For example, the controller circuit 400 generates controlsignals 404 that place the second programmable LED driver circuit 416 ineach configuration.

A brightness of each LED of the one or more LEDs 436 varies inaccordance with the first electric current 420. The first electriccurrent 420 varies in accordance with each configuration of the firstset of configurations. Hence, the brightness of each LED of the one ormore LEDs 436 varies in accordance with each configuration that thefirst programmable LED driver circuit 412 is placed in. The brightnessof each LED of the one or more LEDs 436 also varies in accordance withthe second electric current 424. The second electric current 424 variesin accordance with each configuration of the second set ofconfigurations. Hence, the brightness of each LED of the one or moreLEDs 436 varies in accordance with each configuration that the secondprogrammable LED driver circuit 416 is placed in. By controlling theconfigurations that the first programmable LED driver circuit 412 andthe second programmable LED driver circuit 416 are placed in, using thecontroller circuit 400, the brightness of the LED array can be adjusted.

The first electric current 420 and the second electric current 424 arecombined into a third electric current 428 to drive the one or more LEDs436. For example, the first electric current 420 can be in a range from1 mA to 50 mA. The second electric current 424 can be in a range from 50mA to 500 mA. The third electric current 428 can be in a range from 1 mAto 550 mA. Each LED of the one or more LEDs 426 has a first minimumbrightness responsive to being driven by the first electric current 420(for example, 1 mA). Each LED of the one or more LEDs 436 has a secondminimum brightness responsive to being driven by the second electriccurrent 424 (for example, 50 mA). Each LED of the one or more LEDs 436has a third minimum brightness responsive to being driven by the thirdelectric current 428 (for example, 1 mA). The third minimum brightnessis a lesser of the first minimum brightness and the second minimumbrightness.

Each LED of the one or more LEDs 436 has a first maximum brightnessresponsive to being driven by the first electric current 420 (forexample, 50 mA). Each LED of the one or more LEDs 436 has a secondmaximum brightness responsive to being driven by the second electriccurrent 424 (for example, 500 mA). Each LED of the one or more LEDs 436has a third maximum brightness responsive to being driven by the thirdelectric current 428 (for example, 550 mA). The third maximum brightnessis a greater of the first maximum brightness and the second maximumbrightness.

The one or more LEDs include at least a first LED having a first color(for example, red) and a second LED having a second color (for example,green). The first color is different from the second color. One or moreblue LEDs can also be used to construct the LED array. In someembodiments, the controller circuit 400 programs at least one of thefirst programmable LED driver circuit 412 or the second programmable LEDdriver circuit 416 to adjust a brightness of each LED of the one or moreLEDs 436 within one frame cycle. The frame cycle corresponds to thecycle rate or image frame rate of an electronic display or lightingsystem using the one or more LEDs 436. In other embodiments, thecontroller circuit 400 synchronizes a change to a brightness of each LEDof the one or more LEDs 436 to an output of an electronic display or alighting system using the one or more LEDs 436. For example, in avirtual reality game displayed on a virtual reality headset using theone or more LEDs 436, the controller circuit 400 can synchronize adecrease in a brightness of an LED to the display of a particular imageon the headset.

FIG. 5 illustrates an apparatus for controlling an LED array. Theapparatus illustrated in FIG. 5 includes a controller circuit 500, anLED driver circuit 504, a red LED 508, a green LED 512, a blue LED 516,and an electronic switching circuit 520. The electronic switchingcircuit 520 includes an electronic switch 524, and three resistors 528,532, 536. In some embodiments, the apparatus illustrated in FIG. 5 isused to control a lighting system having an LED array with two or moreunique colors, for example, violet, amber, white, etc.

The LED driver circuit 504 is configured to generate an electric current540 to power the LEDs 508, 512, 516. The controller circuit 500 controlsand operates the LED driver circuit 504 to adjust an amount of theelectric current 540 generated. The LEDs 508, 512, 516 are electricallyconnected to the LED driver circuit 504 to be powered by the LED drivercircuit 504. The electronic switching circuit 520 is electricallyconnected to the LEDs 508, 512, 516. The electronic switching circuit520 is configured to be placed in one of two switching configurations.For example, when the electronic switch 524 is open, the electronicswitching circuit 520 is placed in a first switching configuration. Whenthe electronic switch 524 is closed, the electronic switching circuit520 is placed in a second switching configuration.

The electronic switching circuit 520 directs a portion 544 of theelectric current 540 away from the LEDs 508, 512, 516, such that aremaining portion 548 of the electric current 540 drives each of theLEDs 508, 512, 516. The portion 544 of the electric current 540corresponds to the switching configuration that the electronic switchingcircuit 520 is placed in. For example, in the first configuration, theportion 544 of the electric current 540 is zero.

When the red LED 508 is driven in the second switching configuration,the portion 544 of the electric current 540 corresponds to the voltagedrop across the red LED 508 divided by a resistance of the resistor 528.When the green LED 512 is driven in the second switching configuration,the portion 544 of the electric current 540 corresponds to the voltagedrop across the green LED 512 divided by a resistance of the resistor532. When the blue LED 516 is driven in the second switchingconfiguration, the portion 544 of the electric current 540 correspondsto the voltage drop across the blue LED 516 divided by a resistance ofthe resistor 536. The remaining portion 548 of the electric current 540driving each of the LEDs 508, 512, 516 is, therefore, always less thanthe electric current 540 when the electronic switch is closed. Forexample, when the electric current 540 generated by the LED drivercircuit 504 is in a range from 20 mA to 400 mA, the remaining portion548 of the electric current 540 is in a range from 0 mA to 380 mA. Theminimum brightness of the LEDs 508, 512, 516 in the second configuration(when the electronic switching circuit 520 is used) is, therefore, lessthan the minimum brightness of the LEDs 508, 512, 516 when electronicswitching circuit 520 is not used. The apparatus illustrated in FIG. 5thus provides a lower minimum brightness, greater dynamic brightnessrange, and improved sensitivity control for the LED array as compared totraditional methods.

In some embodiments, the brightness and color characteristics of anelectronic display (or other lighting system) using the apparatusesillustrated in FIGS. 1-5 can be adjusted by characterizing thetemperature and current dependence of each LED and adjusting the mannerin which the electronic display receives and handles the emitted lightfrom the LEDs based on the characterization. These two steps aresometimes referred to as “thermal calibration” or “color calibration” ofthe electronic display. The characterization step can occur during orafter fabrication, e.g., while the electronic display is still in thefactory, by positioning a light detection device (e.g., a spectrometer)at a distance from the eyepiece where the user's eye would receive thelight when the device is in use. The light detection device sequentiallydetects each LED's output light through the electronic display as whilea controller (e.g., a feed forward controller) iterates through multipletemperatures and currents. The output light of the LEDs is analyzed toextract chromaticity and luminance data that are used to characterizeeach LED. When the electronic display is in actual use by the user, thecalibration step is performed by measuring a temperature and adjustingthe LED current and the color computation algorithm based on thecharacterization data as informed by the measured temperature. Detailsof the calibration process and the feed forward control are disclosed inU.S. patent application Ser. No. 16/530,599, which is incorporated byreference herein in its entirety.

FIG. 6 illustrates a method for controlling an LED array. In someembodiments, the process illustrated in FIG. 6 is performed theapparatus illustrated in FIG. 1 . In other embodiments, the processillustrated in FIG. 6 is performed by other apparatuses, such as theapparatuses illustrated in FIG. 2, 3 , or 5.

An LED driver circuit (for example, the LED driver circuit 108)generates 604 an electric current (for example, the electric current116). The LED driver circuit 108 and the electric current 116 areillustrated and described in more detail with reference to FIG. 1 . Theelectric current 116 is for powering one or more LEDs (for example, theone or more LEDs 112) of an LED array. The one or more LEDs 112 areillustrated and described in more detail with reference to FIG. 1 .

One or more electronic switches (for example, the electronic switch 120)place 608 an electronic switching circuit (for example, the electronicswitching circuit 128) in one of multiple switching configurations. Theelectronic switch 120 and the electronic switching circuit 128 areillustrated and described in more detail with reference to FIG. 1 . Theelectronic switching circuit 128 includes a resistor 124. The electronicswitching circuit 128 is electrically connected to the one or more LEDs112. When the electronic switch 120 is open, the electronic switchingcircuit 128 is placed in a first switching configuration in which theelectric current 116 flows through the one or more LEDs 112 to powerthem on one at a time.

The electronic switching circuit 128 directs 612 a portion (for example,the portion 132) of the electric current 116 away from the one or moreLEDs 112 of the LED array. A remaining portion (for example, theremaining portion 136) of the electric current 116 drives the one ormore LEDs 112. The portion 132 of the electric current 116 correspondsto the switching configuration that the 128 is placed in. Each LED has afirst brightness responsive to being driven by the electric current 116.Hence, the minimum brightness limit of the LED array, when theelectronic switching circuit 128 is not used, corresponds to the minimumlimit on the electric current 116. Each LED has a second brightnessresponsive to being driven by the remaining portion 136 of the electriccurrent 116. Hence, the minimum brightness limit of the LED array, whenthe electronic switching circuit 128 is used, corresponds to the minimumlimit on the remaining portion 136 of the electric current 116. Hence,the second brightness is less than the first brightness, and the minimumbrightness limit of the LED array can be reduced when the electronicswitching circuit 128 is used compared to when the electronic switchingcircuit 128 is not used.

FIG. 7 illustrates a method for controlling an LED array. In someembodiments, the process illustrated in FIG. 7 is performed theapparatus illustrated in FIG. 4 .

A controller circuit (for example, the controller circuit 400) places704 a first programmable LED driver circuit (for example, the firstprogrammable LED driver circuit 412) in one of a first set ofconfigurations. The controller circuit 400 and the first programmableLED driver circuit 412 are illustrated and described in more detail withreference to FIG. 4 . For example, the controller circuit 400 generatescontrol signals 408 that place the first programmable LED driver circuit412 in each of the first set of configurations. The first programmableLED driver circuit 412 is electrically connected to one or more LEDs(for example, the one or more LEDs 436) and configured to power the oneor more LEDs 436. The one or more LEDs 436 are illustrated and describedin more detail with reference to FIG. 4 .

In each of the first set of configurations, the first programmable LEDdriver circuit 412 generates 708 a first electric current 420 to powerthe one or more LEDs 436. The first electric current 420 corresponds tothe configuration that the first programmable LED driver circuit 412 isplaced in. The first electric current 420 is illustrated and describedin more detail with reference to FIG. 4 .

The controller circuit 400 places 712 a second programmable LED drivercircuit (for example, the second programmable LED driver circuit 416) ina second one of a second set of configurations. The second programmableLED driver circuit 416 is illustrated and described in more detail withreference to FIG. 4 . For example, the controller circuit 400 generatescontrol signals 404 that place the second programmable LED drivercircuit 416 in each of the second set of configurations. The secondprogrammable LED driver circuit 416 is electrically connected to the oneor more LEDs 436 and configured to power the one or more LEDs 436.

In each of the second set of configurations, the second programmable LEDdriver circuit 416 generates 716 a second electric current 424 to powerthe one or more LEDs 436. The second electric current 424 corresponds tothe configuration that the second programmable LED driver circuit 416 isplaced in.

An electrical network (for example, the electrical network 432) combines720 the first electric current 420 and the second electric current 424into a third electric current 428 to drive the one or more LEDs 436 ofthe LED array. A brightness of each LED varies in accordance with thefirst electric current 420 and each configuration that the firstprogrammable LED driver circuit 412 is placed in. The brightness of eachLED also varies in accordance with the second electric current 424 andeach configuration that the second programmable LED driver circuit 416is placed in. By controlling the configurations that the firstprogrammable LED driver circuit 412 and the second programmable LEDdriver circuit 416 are placed in, the controller circuit 400 adjusts thebrightness of the LED array.

In some configurations, a controller circuit places a first programmableLED driver circuit in one of a first set of configurations. The firstprogrammable LED driver circuit generates a first electric currentcorresponding to the one of the first set of configurations. Acontroller circuit places a second programmable LED driver circuit in asecond one of a second set of configurations. The second programmableLED driver circuit generates a second electric current corresponding tothe second one of the second set of configurations. An electricalnetwork combines the first electric current and the second electriccurrent into a third electric current to drive one or more LEDs of theLED array.

In some configurations, placing the first programmable LED drivercircuit in the one of the first set of configurations adjusts the firstelectric current. Placing the second programmable LED driver circuit inthe second one of the second set of configurations adjusts the secondelectric current.

In some configurations, each LED of the one or more LEDs has a firstminimum brightness responsive to being driven by the first electriccurrent. Each LED of the one or more LEDs has a second minimumbrightness responsive to being driven by the second electric current.Each LED of the one or more LEDs has a third minimum brightnessresponsive to being driven by the third electric current. The thirdminimum brightness equals a lesser of the first minimum brightness andthe second minimum brightness.

In some configurations, each LED of the one or more LEDs has a firstmaximum brightness responsive to being driven by the first electriccurrent. Each LED of the one or more LEDs has a second maximumbrightness responsive to being driven by the second electric current.Each LED of the one or more LEDs has a third maximum brightnessresponsive to being driven by the third electric current. The thirdmaximum brightness equals a greater of the first maximum brightness andthe second maximum brightness.

In some configurations, a brightness of each LED of the one or more LEDsvaries in accordance with each configuration of the first set ofconfigurations. The brightness of each LED of the one or more LEDsvaries in accordance with each configuration of the second set ofconfigurations.

In some configurations, the one or more LEDs include a first LED havinga first color and a second LED having a second color. The first color isdifferent from the second color.

In some configurations, the controller circuit adjusts a brightness ofeach LED of the one or more LEDs of the LED array within one frame cycleof the LED array.

In some configurations, the controller circuit synchronizes a change toa brightness of each LED of the one or more LEDs of the LED array to anoutput of the LED array.

1.-20. (canceled)
 21. An apparatus for controlling a light-emittingdiode (LED) array, the apparatus comprising: an LED driver circuitconfigured to generate an electric current; one or more LEDs of the LEDarray, the one or more LEDs electrically connected to the LED drivercircuit; and an electronic switching circuit electrically connected inparallel to a first LED of the one or more LEDs and configured to: beplaced in one of a plurality of switching configurations; and direct aportion of the electric current away from the first LED of the one ormore LEDs, such that a remaining portion of the electric current drivesthe first LED of the one or more LEDs, and the portion of the electriccurrent corresponds to the one of the plurality of switchingconfigurations, wherein the electronic switching circuit comprises: aplurality of electronic switches electrically connected in a firstparallel configuration; and a plurality of resistors electricallyconnected in a second parallel configuration, each electronic switch ofthe plurality of electronic switches electrically connected to one ormore corresponding resistors of the plurality of resistors.
 22. Theapparatus of claim 21, wherein, when the electronic switching circuit isin use, each LED of the one or more LEDs has a first brightnessresponsive to being driven by the electric current, and each LED of theone or more LEDs has a second brightness responsive to being driven bythe remaining portion of the electric current, the second brightnessless than the first brightness.
 23. The apparatus of claim 21, wherein abrightness of each LED of the one or more LEDs varies in accordance witheach switching configuration of the plurality of switchingconfigurations.
 24. The apparatus of claim 21, wherein one or more ofthe plurality of electronic switches is configured to place theelectronic switching circuit in one of the plurality of switchingconfigurations; and one or more of the plurality of resistors iselectrically connected to one or more of the plurality of electronicswitches and configured to direct the portion of the electric current toa port of the LED driver circuit, such that the portion of the electriccurrent from the one or more of the plurality of resistors and theremaining portion of the electric current driving the one or more LEDscombine at the port of the LED driver circuit.
 25. The apparatus ofclaim 21, wherein the plurality of electronic switches comprises Nelectronic switches, and the plurality of switching configurationscomprises 2N switching configurations, wherein N is greater than orequal to
 1. 26. The apparatus of claim 21, wherein the plurality ofresistors comprises one or more variable resistors.
 27. The apparatus ofclaim 21, wherein the electric current is in a range from 20 mA to 400mA, and the remaining portion of the electric current is in a range from0 mA to 380 mA.
 28. The apparatus of claim 21, wherein the one or moreLEDs comprise a first LED having a first color and a second LED having asecond color, and the first color is different from the second color.29. A method for controlling a light-emitting diode (LED) array, themethod comprising: generating, by an LED driver circuit, an electriccurrent; placing, by one of a plurality of electronic switcheselectrically connected in a first parallel configuration, an electronicswitching circuit in one of a plurality of switching configurations; anddirecting, by the electronic switching circuit, a portion of theelectric current away from a first LED of the LED array, such that aremaining portion of the electric current drives the first LED, and theportion of the electric current corresponds to the one of the pluralityof switching configurations, wherein the electronic switching circuit iselectrically connected in parallel to the first LED, wherein theelectronic switching circuit comprises: the plurality of electronicswitches, and a plurality of resistors, wherein the plurality ofresistors are electrically connected in a second parallel configuration,and each electronic switch of the plurality of electronic switches iselectrically connected to one or more corresponding resistors of theplurality of resistors.
 30. The method of claim 29, wherein, when theelectronic switching circuit is in use, each LED of the one or more LEDshas a first brightness responsive to being driven by the electriccurrent, and each LED of the one or more LEDs has a second brightnessresponsive to being driven by the remaining portion of the electriccurrent, the second brightness less than the first brightness.
 31. Themethod of claim 29, wherein a brightness of each LED of the one or moreLEDs varies in accordance with each switching configuration of theplurality of switching configurations.
 32. The method of claim 29,further comprising: directing, by one or more of the plurality ofresistors, the portion of the electric current to a port of the LEDdriver circuit; and combining, by an electrical network, the portion ofthe electric current from the one or more of the plurality of resistorsand the remaining portion of the electric current driving the one ormore LEDs at the port of the LED driver circuit.